Amorphous alloys have been employed as a material for a magnetic core (core) of a transformer for power distribution, a transformer for electronic and electric circuit, and the like since they exhibit excellent magnetic properties.
Magnetic cores made of amorphous alloys (hereinafter, referred to as the “amorphous alloy magnetic core”) can suppress the loss of electric current at the time of no load to about ⅓ as compared to magnetic cores made of silicon steel plates (electromagnetic steel plate), and they have been thus expected as a magnetic core adaptable to energy saving in recent years.
An amorphous alloy thin strip (amorphous alloy ribbon) to be used in fabrication of amorphous alloy magnetic cores is manufactured by discharging a molten alloy onto a cooling roll that is made of a copper alloy and rotates from a nozzle by a single roll method and rapidly cooling the molten alloy.
The amorphous alloy magnetic cores are often subjected to a heat treatment after being fabricated by layering amorphous alloy thin strips one on another in order to impart proper magnetic properties to the amorphous alloy magnetic cores.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2007-234714 discloses the relation between the heat treatment temperature of an amorphous alloy magnetic core and the iron loss (core loss) or Hc (coercive force) of the amorphous alloy magnetic core.
In addition, Japanese National-Phase Publication (JP-A) No. 2001-510508 discloses the relation between the heat treatment temperature of an amorphous alloy magnetic core and the excitation force of the amorphous alloy magnetic core.
In addition, with regard to the amorphous alloy magnetic core described above, it is disclosed in Japanese Patent Publication (JP-B) No. H7-9858 that the end portion in the width direction of the layered amorphous alloy thin strips is covered with a bonding layer for the purpose of suppressing the missing of a part of the end portion of the layered amorphous alloy thin strips, and the like.